Photographic direct-print emulsion comprising a hydrazine compound and formaldehyde

ABSTRACT

PHOTOGRAPHIC DIRECT-PRINT EMULSIONS COMPRISING A HYDRAZINE COMPOUND AS A HALOGEN ACCEPTOR AND AT LEAST ONE MOLE OF FORMALDEHYDR PER MOLE OF SAID HYDRAZINE COMPOUND.

United States Patent Ofiice Patented Feb. 16, 1971 PHOTOGRAPHIC DIRECT-PRINT EMULSION COM- PRISING A HYDRAZINE COMPOUND AND FORMALDEHYDE Richard W. Karlson, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 2, 1967, Ser. No. 671,953

Int. (ll. G03c 1/02 US. Cl. 9694 7 Claims ABSTRACT OF THE DISCLOSURE Photographic direct-print emulsions comprising a hydrazine compound as a halogen acceptor and at least one mole of formaldehyde per mole of said hydrazine compound.

This application relates to photographic, direct-print compositions. In one aspect this invention relates to a direct-print silver halide emulsion containing hydrazine type halogen acceptors. In another aspect this invention relates to a means for improving the discrimination (DmaxDmin) in direct-print emulsions which contain hydrazine type halogen acceptors.

It is known in the prior art to use hydrazine compounds in direct-print emulsions as halogen acceptors. However, hydrazine compounds have not been generally used commercially in direct-print emulsions for some end uses because the effectiveness of hydrazines as halogen acceptors in direct-print emulsions generally decreases as the coating is aged, especially at elevated temperatures. Improved means for improving the photographic and physical characteristics of direct-print emulsions containing hydrazine compounds as halogen acceptors are desirable.

Therefore, it is an object of this invention to provide means to improve the photographic and physical properties of direct-print emulsions containing hydrazine compounds.

It is another object of this invention to provide new direct-print compositions.

It is another object of this invention to provide new direct-print silver halide emulsions having improved incubation stability.

It is still another object to provide new direct-print emulsions having improved halogen acceptors.

These and other objects of the invention are achieved with a direct-print silver halide composition comprising a hydrazine compound and from about 1 to about 3 moles of formaldehyde per mole of said hydrazine compound. Direct-print emulsions comprising this combination of ingredients exhibit improved image discrimination after incubation. The improved effectiveness of formaldehyde in combination with hydrazine compounds as halogen acceptors in direct-print emulsions is quite unexpected, especially since the prior art contains several suggestions that adverse photographic properties are obtained when formaldehyde is used as a hardener in emulsions containing hydrazine compounds. Therefore, it is, indeed, unexpected that concentrations of formaldehyde above the level normally used for hardening emulsions would improve discrimination in direct-print emulsions.

Suitable silver halide emulsions used in photographic elements stabilized according to this invention are those which will function as direct-print emulsions. Suitable silver halides include internally sensitized silver bromide, silver bromo iodide, silver chlorobromide, silver chlorobromoiodide and the like. The preferred emulsions are those wherein the halide of the silver is predominantly bromide. In a typical embodiment, the preferred emulsions have higher internal sensitivity than surface sensitivity as described by Hunt in Photographic Science and Engineering, vol. 5, No. 2, MarchApril 1961, pp. 104-108. For a description of suitable emulsions, reference is made to Davey et al., US. Pat. 2,592,250, issued Apr. 8, 1952; US. Pat. 3,206,316; Porter et al., U.S. Pat. 3,206,313; Kitze, Belgium Pat. 689,515 issued Jan. 13, 1967; Glafkides, Photographic Chemistry, vol. 1, pp. 31-32, Fountain Press, London; and in McBride, US. Pat. 3,271,157, issued Sept. 6, 1966, and US. Pat. 3,287,137.

The direct-print emulsions of this invention contain hydrazine compounds as halogen acceptors. Suitable hydrazine compounds of this invention include those compounds having the general formula:

in which at least two of the Rs are hydrogen atoms and when less than four Rs are hydrogen atoms the remaining Rs are aryl, aralkyl, acyl or carboxylic acid amide groups; including the acid salts of the compounds represented by this formula. In one embodiment the hydrazine compound preferably does not contain more than one aralkyl, acyl or carboxylic acid amide group although it may contain either one or two aryl groups. In another embodiment the hydrazine compound is preferably hydrazine dihydrochloride (N H 2HC1) Typical hydrazine compounds which can be used according to this invention include hydrazine, hydrazine dihydrochloride, phenyl hydrazine dihydrochloride, phenylhydrazine hydrochloride, p-bromphenylhydrazine hydrochloride, p-chlorphenylhydrazine hydrochloride, 2,5-dichlorophenyl hydrazine, p-tolyl hydrazine hydrochloride, p-toluene sulfonyl hydrazine, a-naphthylhydrazine, pacetylphenylhydrazine, a-benzyl-a-phenylhydrazine hydrochloride, n-amyl succinyl dihydrazide, sodium sulfosuccinyl dihydrazide, hydrazine dicarbonic dihydrazide, hydrazobenzene, p-hydrazinobenzoic acid, p-hydrazinobenzene sulfonic acid (sodium salt), phenylhydrazine-msulfonic acid (sodium salt), p-[p-(methylsulfonamido) ethyl] phenyl hydrazine, p-methyl-sulfonamido-phenylhydrazine hydrochloride, triphenyl phosphonium chloride acetohydrazide, N,N-diphenyl hydrazine and p-diphenyl hydrazine and the like.

The concentration of hydrazine type compounds utilized in the emulsions of the invention can be widely varied in accordance with the usual practice. Generally, about .1 to about mole percent, and preferably about 1 to about 50 mole percent, based on the silver halide in the emulsion, of the hydrazine compounds are used.

It is understood that direct-print emulsions as defined in this invention refer to those emulsions which when given a brief imagewise high intensity exposure of about 0.5 m.c.s. to about 500 m.c.s. will photodevelop in room light to produce a discernable image to the eye.

Various colloids can be used as vehicles or binding agents in preparing the silver halide emulsions of this invention. Satisfactory colloids which can be used for this purpose include any of the hydrophilic colloids generally employed in the photographic field, including, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers and the like. In addition to the above hydrophilic colloids, the vehicle or binding agent can also contain hydrophobic colloids, such as dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include water-insoluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and the like.

The above-described emulsions of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include glass, metal, paper, polyolefin-coated paper, cellulose nitrate film, cellulose acetate film, polystyrene film, polyester films such as polyethylene terephthalate film, heat resistant polymeric films such as high temperature polyester, polyimide, polycarbonate films, and the like.

The invention can be further illustrated by the following examples of preferred embodiments thereof, although it will be understood that the examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise indicated.

EXAMPLE 1 A direct-print silver chlorobromide emulsion (about mole percent chloride and about 95 mole percent bromide) is prepared according to McBride, US. Pat. 3,271,157 issued Sept. 6, 1966. Hydrazine dihydrochloride (N H -2HC1) is added to the emulsion at a concentration of .125 mole of hydrazine dihydrochloride per mole of silver halide. Formaldehyde is then added at the concentrations listed in the table. The emulsion is coated at 256 mg. of silver per ft. and 565 mg. of gelatin per ft? on unhardened paper stock. These coatings were given a bar exposure with a Heiland Strobonar I flash lamp at eight feet (approximately 100 m.c.s. for 2 10 sec.) and photodeveloped for twenty minutes at 5060 foot candles of cool white fluorescent light.

Discrimination (D MAX-DMIN) Formaldehyde 7 days 120 F./ (moles/Ag mole) Fresh 55% RH Level of formaldehyde normally used to harden emulsions.

It is apparent that the formaldehyde-hydrazine compound combination improves discrimination upon incubation in direct-print emulsions.

Similar results are obtained when phenyl hydrazine hydrochloride, 2,5-dichlorophenyl hydrazine, p-toluene sulfonyl hydrazine, 'y-naphthylhydrazine, and hydrazobenzene are used in combination with formaldehyde in direct-print emulsions.

The invention has been described in considerable detail with reference to preferred embodiments thereof, but

4 it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hercinabove and as defined in the appended claims.

I claim:

1. A direct-print composition comprising a silver halide hydrazine halogen acceptor and formaldehyde at a concentration from about 1 to about 3 moles per mole of said hydrazine.

2. A direct-print silver halide composition according to claim 1 wherein said composition comprises about .1 mole to about 100 moles of said halogen acceptor per mole of silver halide.

3. A direct-print silver halide composition according to claim 1 wherein said composition comprises from 1 to mole percent of said halogen acceptor per mole of silver halide.

4. A direct-print composition according to claim 1 wherein said hydrazine compound is hydrazine dihydrochloride.

5. A direct-print composition according to claim 1 wherein said hydrazine compound has the general formula:

wherein at least two R's are hydrogen atoms and the remaining two R's can be aryl, aralkyl, acyl or carboxylic acid amide groups and the acid salts of this compound.

6. A direct-print silver halide composition according to claim 1 wherein the halide of said silver halide is predominantly bromide.

7. A direct-print silver halide composition according 'to claim 1 which comprises silver halide grains having a predominant amount of radiation sensitivity internal to said grains.

References Cited UNITED STATES PATENTS 2,588,982 3/1952 Ives 96-64 3,458,317 7/1969 DitZer et al. 9694 NORMAN G. TORCHIN, Primary Examiner J. R. HIGHTOWER, Assistant Examiner US. Cl. X.R. 96107 

